P0406 means the EGR position sensor 'A' is sending a voltage above its normal operating range, typically above 4.5V. This is usually caused by an open signal wire, a sensor shorted to its 5V reference internally, or a sensor that has failed in the open position.
P0406 means the EGR position sensor 'A' is sending a voltage above its normal operating range, typically above 4.5V. This is usually caused by an open signal wire, a sensor shorted to its 5V reference internally, or a sensor that has failed in the open position.
P0406 est un code defaut lie a emissions, classe en gravite moderate. Lorsque le calculateur de ton vehicule detecte cette condition, il enregistre P0406 et allume le voyant moteur.
Si ton vehicule a declenche P0406, tu peux remarquer un ou plusieurs de ces symptomes :
Voici les causes les plus courantes de P0406, classees selon la probabilite qu'elles soient en cause :
En general oui, pour des trajets courts. Driveable. P0406 means the EGR position sensor (sensor A) is reporting a voltage higher than the expected range. The ECU loses trust in the EGR feedback and disables the system, causing rough idle and possible limp mode on diesels. Failed emissions test is guaranteed.
Suis ces etapes pour identifier la cause profonde de P0406 :
Les couts de reparation de P0406 varient selon la cause profonde et ton vehicule. Voici des estimations courantes :
Prix estimes au March 2026. Les couts varient selon la region, le vehicule et le garage.
P0406 se comporte differemment selon ton vehicule. Selectionne ta voiture ci-dessous pour des causes propres au modele, les problemes connus et des estimations de couts ajustees :
2007–2024
The N47 and B47 320d EGR sensor fails high (P0406) less often than low (P0405), but when it does it usually means the integrated sensor has failed internally rather than a wiring issue. The EGR connector is buried under the intake manifold support, requiring partial disassembly for inspection. ISTA or Carly adaptation reset is mandatory after valve replacement on the B47.
Couts estimes pour les proprietaires de BMW 3 Seriesajuste a la hausse par rapport a la moyenne en raison du prix des pieces specifiques a BMW
Prix estimes au March 2026. Les couts varient selon la region, le vehicule et le garage.
2009–2024
EA189 and EA288 TDI Golfs occasionally throw P0406 after harness work or accessory installation that disturbs the EGR connector. Always check that the connector is fully clicked in before replacing parts. On EA288 (2014+), the connector lock tab can crack from age, allowing the connector to back out under engine vibration. VCDS measured value block confirms the sensor voltage.
Couts estimes pour les proprietaires de Volkswagen Golfajuste a la hausse par rapport a la moyenne en raison du prix des pieces specifiques a Volkswagen
Prix estimes au March 2026. Les couts varient selon la region, le vehicule et le garage.
2008–2024
B8 and B9 A4 2.0 TDI suffer the same P0406 failure modes as the Golf, plus restricted access due to the larger intake manifold. On 3.0 TDI V6 models, P0406 may apply to either bank, so always read the freeze frame to confirm which side. Adaptation reset via VCDS or ODIS is required after sensor or valve service.
Couts estimes pour les proprietaires de Audi A4ajuste a la hausse par rapport a la moyenne en raison du prix des pieces specifiques a Audi
Prix estimes au March 2026. Les couts varient selon la region, le vehicule et le garage.
2010–2024
OM651 Sprinter EGR sensor open-circuit failures are less common than shorts (P0405), but when they appear they often correlate with a recent winter where road salt damaged the connector pins. Repair attempts at the harness rarely last, so most workshops fit a new pigtail connector with heat-shrink seals and a fresh EGR valve. XENTRY adaptation reset is mandatory.
Couts estimes pour les proprietaires de Mercedes Sprinterajuste a la hausse par rapport a la moyenne en raison du prix des pieces specifiques a Mercedes-Benz
Prix estimes au March 2026. Les couts varient selon la region, le vehicule et le garage.
Ces codes apparaissent souvent avec P0406 ou indiquent des problemes connexes :
P0405 means the signal is too low (below ~0.2V), usually a short to ground or failed sensor. P0406 means the signal is too high (above ~4.5V), usually an open wire, missing ground, or sensor failed open. Diagnostic steps are similar but the failure modes are opposite.
Yes, short distances. The ECU disables EGR control, so the engine runs without EGR. Expect rough idle and possible limp mode on diesels. Long-term driving accelerates intake carbon buildup, especially on direct-injection engines. Plan the repair within a few weeks.
No. EGR delete is illegal across the EU and UK, raises NOx emissions above legal limits, and fails periodic technical inspection (TÜV, ITV, TA, SKP). It can also void insurance and prevent vehicle registration transfer. Always repair the sensor or valve properly.
Two common reasons. First, EGR adaptation values were not reset after the new valve was fitted (required on BMW, Mercedes, VAG). Second, the carbon buildup that caused the original sensor stress is still present and damages the new sensor within months. Always clean the intake passages alongside any valve replacement.
Clean a carboned diesel EGR valve yourself for €10-30. Symptoms, step-by-step removal, when to clean vs replace, and how to verify the fix with OBD2.
EGR deletion is the hardest of the three diesel emissions cheats to detect with OBD2. Here is what the scan tool reveals, what it cannot, and three physical checks that close the gap.
Branche un adaptateur OBD2 Bluetooth standard, scanne les codes et obtiens un diagnostic par IA avec niveaux de gravite et estimations des couts de reparation.
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